[ale] Realigning a partition with data

[Alex Carver]

That would be fun to attend but a bit far to travel.

On 2017-04-24 08:02, Charles Shapiro wrote:
> Atlanta Vintage Computer Festival is this weekend. ( https://atlhcs.org/ ).
> 
> -- CHS
> 
> 
> On Sun, Apr 23, 2017 at 4:45 PM, Alex Carver <agcarver+ale at acarver.net 
> <mailto:agcarver+ale at acarver.net>> wrote:
> 
>     In this case the old drive was MSDOS partition with 512b blocks so it's
>     not 4k aligned.  The file system itself is ext2.  When I imaged the old
>     drive with ddrescue, I pulled the entire drive in so I'd have the boot
>     sector and the primary partition (there was only two partitions on the
>     original drive and one was swap).  I killed off the swap partition then
>     stretched out the main partition a bit to accommodate the contents of a
>     second drive that was installed (single partition as well).  I was more
>     concerned about the block erasing during TRIM in the SSD with unaligned
>     sectors.
> 
>     It's mainly used as the network syslog server to record all the logs
>     from various network devices (cameras, phones, etc.), some data logging
>     from remote sensors (database), plus I do some internal web applications
>     with it.  Not really heavy usage.
> 
>     I've got plenty of old machines floating around with 5.25 floppies or
>     other storage media.  :)  In rough order of age of all my functional
>     machines:
> 
>     Timex Sinclair (tape drive from a TRS-80 is floating around though the
>     TRS-80 is no longer here)
>     [Used to have a NorthStar branded CP/M machine with hard-sector 5.25
>     floppies and integrated green screen -- I taught myself dBase III on it
>     and cataloged all my electronic parts with it.  It's long gone but it
>     was functional]
>     Emerson branded 80286 (this became a modem server though it needs fixing up)
>     NeXT slab
>     2x Sun IPXes with external enclosures (one of them is my network GPS clock)
>     Unbranded (from parts) 386DX with 387 coproc
>     Packard Bell branded 486SX (now with a 486DX2/66 chip)
>     Unbranded Pentium II 266 (for experiments)
>     4x Sun Enterprise 220Rs with dual UltraSPARC II processors (lots of
>     experiments)
>     1x Sun SparcStation 20 (RAID server using 2 Sun A1000 arrays)
>     Unbranded AMD K6 (the topic of conversation)
>     Toshiba Satellite 1900 series laptop
>     Averatec laptop
>     Unbranded Pentium 4 (previous desktop)
>     3x Raspberry Pi B+
>     Unbranded Core i7-3770 Ivy Bridge (current desktop)
> 
>     On 2017-04-23 13:10, DJ-Pfulio wrote:
>      > I don't think alignment matters on SSDs. They are so fast.
>      >
>      > I've done this with gparted, but always made a full partition backup
>      > using fsarchiver first.  Didn't need the backup, but ... I'm pretty
>      > experienced with the tools.
>      >
>      > Also, the underlying file system matters.  XFS/btrfs seem to have the
>      > most issues.  EXT3/4 seem to be well supported for things like this.  IMHO.
>      >
>      > gparted and parted have always handled alignment issues. I heard that
>      > fdisk started sometime after they added GPT support (whenever that was).
>      > I've never used gdisks after seeing all the problems people had with it.
>      >  Heard that fdisk is safe on GPT again, for the latest distros.
>      >
>      > I have a K2/200 around here somewhere. Keep it for the 5.25in floppy.
>      > Never know when that will be needed again.  That machine also has an
>      > Adaptec 2940u SCSI card. ;)
>      >
>      > On 04/23/2017 02:56 PM, Alex Carver wrote:
>      >> True, I just wondered if there was a way given that parted/resize2fs
>      >> both worked pretty well with data on a partition (I ddrescue'd the old
>      >> drive to the SSD then grew the partition).
>      >>
>      >> However, after running a couple I/O tests on the drive I'm not going to
>      >> bother with the realignment.  I'm getting read speeds of about 160
>      >> MB/sec and write speeds of 116 MB/sec.  Given the age of the machine
>      >> that's pretty good (AMD K6 with a PCI SATA card and SATA SSD to replace
>      >> the on-board IDE and old Maxtor drives)
>      >>
>      >> On 2017-04-23 05:04, Jim Kinney wrote:
>      >>> I would not consider realignment safe with data on the sectors that are
>     soon to
>      >>> be outside the partition.
>      >>>
>      >>> On Apr 23, 2017 2:00 AM, "Alex Carver" <agcarver+ale at acarver.net
>     <mailto:agcarver%2Bale at acarver.net>
>      >>> <mailto:agcarver%2Bale at acarver.net
>     <mailto:agcarver%252Bale at acarver.net>>> wrote:
>      >>>
>      >>>     Just swapped out a spinning drive for an SSD but I probably need to
>      >>>     realign the partitions.  Currently everything is in one partition
>     at the
>      >>>     start of the disk but it's on sector 63.  I can pop the disk out and
>      >>>     plug it into another machine to do this but I'd like to slide the
>      >>>     partition over to the right spot (assuming this doesn't affect the boot
>      >>>     process).  I haven't found a way to do this as nearly every page I find
>      >>>     talks about having parted align new partitions but not those that
>     have data.